Young's modulus, denoted by E, is a measure of the stiffness of a solid material. It is defined as the ratio of stress to strain in a material that is behaving elastically. Stress is the force applied per unit area, and strain is the deformation experienced by the material in response to the applied stress.
Let's break down the dimensions for Young's modulus:
Stress: Stress is defined as force per unit area. Thus, the dimension of stress can be expressed as:
Stress = Force / Area
The dimension of force is given by mass × acceleration, i.e., Force = MLT-2 (where M is mass, L is length, and T is time).
The dimension of area is length × length = L2.
Therefore, the dimension of stress is:
Stress = (MLT-2) / (L2) = ML-1T-2
Strain: Strain is the ratio of the change in length to the original length and is dimensionless because it is a ratio of two lengths.
Thus, the dimension of strain is simply 1 (dimensionless).
Since Young's modulus is the ratio of stress to strain, its dimension is the same as that of stress. Therefore, the dimension of Young’s modulus E is:
ML-1T-2